HD 121056
HD 121056, or HIP 67851, is an aging giant star with a pair of orbiting exoplanets located in the southern constellation of Centaurus. This star is dimly visible to the naked eye with an apparent visual magnitude of 6.17. It is located at a distance of 209 light years from the Sun, based on parallax measurements, and is drifting further away with a radial velocity of 5.6 km/s.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Centaurus |
| Right ascension | 13h 53m 52.06131s |
| Declination | −35° 18′ 51.6918″ |
| Apparent magnitude (V) | 6.17 |
| Characteristics | |
| Evolutionary stage | giant star |
| Spectral type | K0 III |
| B−V color index | 1.01 |
| Astrometry | |
| Radial velocity (Rv) | 5.60±0.13 km/s |
| Proper motion (μ) | RA: −295.304±0.040 mas/yr Dec.: −68.458±0.058 mas/yr |
| Parallax (π) | 15.6261 ± 0.0418 mas |
| Distance | 208.7 ± 0.6 ly (64.0 ± 0.2 pc) |
| Absolute magnitude (MV) | +2.08 |
| Details | |
| Mass | 1.60±0.18 M☉ |
| Radius | 5.72 R☉ |
| Luminosity | 15.8 L☉ |
| Surface gravity (log g) | 3.261±0.105 cgs |
| Temperature | 4,867±49 K |
| Metallicity | [Mg/H] 0.286±0.05 dex |
| Metallicity [Fe/H] | 0.020±0.031 dex |
| Rotational velocity (v sin i) | 2.38±0.51 km/s |
| Age | 5.46 Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
The spectrum of HD 121056 presents as an evolved K-type giant star with a stellar classification of K0 III. It is presently ascending the red-giant branch, having exhausted the supply of hydrogen at its core. The star is about 5.5 billion years old and is spinning with a projected rotational velocity of 2.4 km/s. HD 121056’s concentration of heavy elements is similar to the Sun, with a metallicity Fe/H index of 0.020±0.031, although the star is enriched in lighter rock-forming elements like magnesium and aluminum. It has 1.6 times the mass of the Sun and has expanded to 5.72 times the Sun's radius. The star is radiating 15.8 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,867 K.